Three Things You Didn't Know About: Fertilizer. (2013). The History Channel website. Retrieved 4:13, May 18, 2013, from http://www.history.com/shows/modern-marvels/videos/playlists/three-things-you-didnt-know-about.
Three Things You Didn't Know About: Fertilizer. [Internet]. 2013. The History Channel website. Available from: http://www.history.com/shows/modern-marvels/videos/playlists/three-things-you-didnt-know-about [Accessed 18 May 2013].
“Three Things You Didn't Know About: Fertilizer.” 2013. The History Channel website. May 18 2013, 4:13 http://www.history.com/shows/modern-marvels/videos/playlists/three-things-you-didnt-know-about.
“Three Things You Didn't Know About: Fertilizer,” The History Channel website, 2013, http://www.history.com/shows/modern-marvels/videos/playlists/three-things-you-didnt-know-about [accessed May 18, 2013].
“Three Things You Didn't Know About: Fertilizer,” The History Channel website, http://www.history.com/shows/modern-marvels/videos/playlists/three-things-you-didnt-know-about (accessed May 18, 2013).
Three Things You Didn't Know About: Fertilizer [Internet]. The History Channel website; 2013 [cited 2013 May 18] Available from: http://www.history.com/shows/modern-marvels/videos/playlists/three-things-you-didnt-know-about.
Three Things You Didn't Know About: Fertilizer, http://www.history.com/shows/modern-marvels/videos/playlists/three-things-you-didnt-know-about (last visited May 18, 2013).
Three Things You Didn't Know About: Fertilizer. The History Channel website. 2013. Available at: http://www.history.com/shows/modern-marvels/videos/playlists/three-things-you-didnt-know-about. Accessed May 18, 2013.